I'm not sure it was his first Haskell program, if it was it's pretty impressive that he used INLINE, understood minute differences between Random libraries, profiling, threadscope, etc..
It was indeed my first Haskell program. So I'd take your comment as compliment. I have been a long time C++ programmer (https://stackoverflow.com/users/415784/nawaz), so I know what kind of tools one should look for in another language when it comes to making the code performant. So that helped me.
Pretty amazing how you were able to use the appropriate tooling to a great effect right off the bat!